TRACHYMEDUS-ffi — AGLANTHA, AMPHOGONA. 



405 



Lesson's Circe elongata is probably identical with Haeckel's Agliscra data, and Vanhoffen's 

 Agltscra ignea from the Indian Ocean may possibly be a stage in the growth of the same 

 dusa. Allman's Circe invertens from off the south coast of Ireland is probably identical 



medusa 



with this medusa, 



Aglantha ignea. 



Agliscra ignea, VanhSffdj, Wissen. Ergeb. deutsch. Tiefsee Expedition, Dampfer Valdivia,Bi.%, Lfg. I, p. 76, taf. 9, fig. 10. 



Bell 14 mm. high, 7 mm. wide. 32 tentacles, 8 large radial and 24 small interradial. 

 Lithocysts ( ?) 8 narrow, straight radial-canals with 8 linear gonads attached throughout their 

 entire lengths to middle halves of radial-canals. Manubrium half as long as the depth of the 

 bell-cavity, with 4 simple lips. Velum very wide and projecting beyond the bell-margin. 

 Color of entodermal lamella and all entoderm bright-red. Tropical Indian Ocean, 750 to 

 1,000 fathoms. This may be a stage in the growth of A. elongata ( ?). (See text-figure 256.) 



Genus AMPHOGONA Browne, 1904. 



Amphogona, Browne, 1904, Fauna and Geog. Maldive and Laccadive Archipelagoes, vol. 2, pp. 724. 739-— Bic.elow, H. B., 

 1909, Mem. Mus. Comp. Zool. at Harvard College, vol. 37, p. 125. 



The type species is Amphogona apsteini of the Indian Ocean, Maldive Islands to Sumatra. 

 This was described by Vanhoffen, 1902, as Pantachogon apsteini. 



GENERIC CHARACTERS. 



Aglaurinae with 8 gonads upon the subumbrella parts of the 8 radial-canals. 4 of the 

 gonads are male and alternate with 4 female gonads. 



This genus is closely related to Aglantha, but is separated by its bisexual gonads. Browne 

 discovered this fact upon sectioning the gonads. It is known, however, that this bisexual 

 condition is not constantly present, for Bigelow sectioned a similar medusa and found all ot 

 the 8 gonads to be of one sex. 



Amphogona apsteini Browne. 

 Pantachogon apsteini, Vanhoffen, 1902, Wissen. Ergeb. deutsch. Tiefsee Expedition, Dampfer Valdivia, Bd. 3, Lfg. I, p. 65, 



taf. 10, fig. 18; taf. n, fig. 28. 

 Amphoeon apsteini, Browne, 1904, Fauna and Geog. Maldive and Laccadive Archipelagoes, vol. 2, p. 740, plate 54, fig. 5; plate 



56, fig. 1; plate 57, figs. 10-15— Bigelow, H. B., 1909, Mem. Mus. Comp. Zool. at Harvard College, vol. 37, p. 126, 



plates 2, 34, 45. 



Bell somewhat flatter than a hemisphere, 4.25 mm. wide, 1.75 mm. high. Bell-walls thin. 

 About 70 marginal tentacles, similar each to each and somewhat shorter than bell-radius, 

 filiform and ringed at fairly regular intervals by nematocysts; their entoderm consists of a 



single row of chordate cells. About 16 to 20 marginal 

 sense-organs arise from bell-margin between thetentacles, 

 1 to 3 in each octant. Each marginal sense-organ con- 

 sists of a club with a vesicular cavity containing a single 

 spherical concretion. Velum is quite broad. 8 straight, 

 slender radial-canals and a simple ring-canal. Stomach 

 small, mounted upon a narrow, tapering peduncle down 

 which the 8 radial-canals extend. The mouth is about 

 Fig. 257— Amphogona apsteini, after Vanhoffen, at j eve | f ve l ar opening; 4 simple, short, recurved lips. 



in Tiefsee Expedition Valdivia. rr , n , r . , „ J J C. ~ *-U« 9 



The 8 sausage-shaped gonads are suspended from the 8 

 radial-canals near the ring-canal. In Browne's medusae 4 of these gonads are male and they 

 alternate with 4 female gonads, every other radial-canal bearing a gonad of opposite sex. In 

 Vanhoffen's specimens, 4 interradial gonadswere small and 4 on the perradial canals were larger, 

 but in Browne'swell-developed medusa? the gonadswere all of equal size. The male and female 

 gonads appear to be equally advanced in development at one and the same period. This is 

 one of the few cases of hermaphroditism in Hydromedusae, other examples being found in 

 Eleutheria and Cladonema. Bigelow finds the gonads of a medusa similar to Browne's 

 Amphogona to be unisexual. The hermaphroditism may, therefore, be only an aberration 

 or a temporary matter, as in Cladonema. The medusa is colorless. 



